Process control for stamping

Stamping industry is a long-established, widely used industrial process for economical high-volume production. It is used extensively in the automotive industry/building hardware industry/LED parts / Motor parts/3C parts ,

As well as for production of white goods and many other products.

We would like to present an approach, based on process control, to improve stamped part quality at reduced cost by eliminating tearing, wrinkling and springback. The concept is straight-forward: measure punch forces and then adjust the blank holder forces at various locations around its periphery and at various times during the stamping process to properly control the draw-in of blank material into the die. Of course, how to do this is the challenge! We would like to show in detail how this simple goal can be achieved through real-time control technology.

A reconfigurable set of hydraulic actuators is placed under the die to enable the control of the bland holder forces at various locations around the die periphery. These blank holder forces at each actuator are varied during the short duration of the press stroke. The careful design of a controller, termed the machine controller, is needed to ensure that the desired blank bolder forces are achieved at each hydraulic actuator and at each instant in time during the press stroke. Furthermore, we also measure the punch force during stamping, and design another controller, termed the process controller, to ensure that the desired punch force values are achieved during stamping despite the presence of disturbances. Maintaining the desired punch force leads to consistent draw-in of blank material and improves stamped part quality by eliminating wrinkling, tearing and springback.

We would like to show the methods for designing these controllers, and present experimental validation results from die try-out tests, the proposed system has also been evaluated in pilot tests in production and has also been shown to improve the formability of hard-to-form materials, such as lightweight alloys.